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86 m a s s a g e & b o d y wo r k s e p te m b e r/o c to b e r 2 0 2 1 One of the more debilitating hand conditions is trigger finger or thumb. In this painful condition, the tendons of the finger or thumb cannot bend or straighten smoothly due to thickening, swelling, or nodules in the tendon, its synovial sheath, or the connective tissue bands around the finger called pulleys. Trigger finger can be an overuse syndrome or a result of another systemic problem. As we will see, the simple process of grasping objects requires a complex anatomical and mechanical interface to make the fingers function with precision grip. Trigger finger is not as common as other wrist and hand problems, like carpal tunnel syndrome, but can be incapacitating and painful. When the signs and symptoms are recognized early, less invasive treatment may be successful and prevent the need for surgery. ANATOMICAL BACKGROUND Understanding trigger finger starts with comprehending the unique system of tendons and connective tissues in the fingers and thumb that act like ropes and pulleys. Grasping objects requires the joints bend in flexion. The finger and thumb flexor tendons run along the anterior surface of the fingers or thumb. These tendons are tethered close to the bones by connective tissues referred to as pulleys. Finger Pulleys. In the fingers, the pulleys are found at eight locations from the metacarpophalangeal (MCP) joint to the distal phalanx. The thumb is generally considered to have three primary pulleys, although some recent anatomical studies have described a fourth pulley in the thumb. 1 Let's take a look at these pulleys, how they work, and their role in trigger finger. Annular Pulleys. There are five pulleys in the fingers, called annular pulleys, named A1 through A5 (Image 1). The A1, A3, and A5 pulleys are smaller and considered minor pulleys (primarily due to size, not importance). The A2 and A4 pulleys are larger and are sometimes called the major pulleys. The A1, A3, and A5 pulleys are located at the MCP, the proximal interphalangeal (PIP) joint, and the distal interphalangeal (DIP) joints, respectively. The A2 and A4 pulleys are located in the middle of the proximal and middle phalanx, respectively (Image 1). The thumb contains just three primary pulleys: The A1 and A2 pulleys are like those of the fingers and an oblique pulley sits between them (Image 2). Cruciate Pulleys. In the fingers, a second set of connective tissue pulleys, called cruciate pulleys, give additional support and stability to the tendons. The term cruciate means cross, and you can see by their structure where they get their name (Image 1). The cruciate pulleys are much smaller than the annular pulleys. There are three cruciate pulleys, designated as C1, C2, and C3. Their role in improving the flexor tendon's angle of pull is not significant, so if they are damaged, finger movement is not impaired as much. With all these connective tissues crossing over the tendons, there is significant friction between the tendon and the pulleys. The tendons are enclosed in a synovial sheath to reduce adverse friction. The sheath is in contact with the connective tissue pulleys, and the tendon slides technique | CLINICAL EXPLORATIONS Trigger Finger By Whitney Lowe Annular and cruciate pulleys of the fingers. Image from 3D4Medical's Complete Anatomy application. 1 A1 C1 A3 C2 A4 A5 C3